The invention is based on a method for clamping a pipe with a hose or a pipe with the aid of a compression sleeve.
Connections between a hose and a pipe which are produced with the aid of a compression sleeve are, for example, required in braking systems in motor vehicles, hydraulic devices or the like. Since these connections are produced in very large quantities and they sometimes deal with components relevant to the safety of the system, high quality and safety standards must to be met reliably and the costs for producing the compressed connection must be low.
It is known to clamp a pipe with a hose with the aid of a compression sleeve by using a compression tool that acts radially upon the compression sleeve surrounding the outside of the hose. The clamping is stopped as soon as the jaws of the compression tool have reached a certain position. This means that the pipe, the hose and the compression sleeve are pressed together to a certain degree. In this case, diameter and wall thickness variances of the pipe and the hose as well as manufacturing tolerances of the compression sleeve are not taken into consideration. Since each of the three aforementioned components has relatively high manufacturing tolerances, the forces with which the pipe, the hose and the compression sleeve are pressed together and consequently the quality of the connection between the pipe and the hose vary. This requires expensive quality assurance measures and results in relatively high costs due to rejected parts.
The invention aims to make available a method for clamping a pipe with a hose or a pipe with the aid of a compression sleeve which can be easily carried out and still ensures a very high quality standard of the connection between the pipe and the hose.
According to the invention, this objective is attained with a method for clamping a pipe and a hose or a second pipe with the aid of a compression sleeve high, in which
a compression tool that acts upon the compression sleeve in the radial direction is advanced,
the radial force F between the compression tool and the compression sleeve is determined, and
the compression tool is advanced by a residual compression distance sR after a predetermined value a for the radial force F is reached.
This method provides the advantage that a certain radial force between the compression tool and the compression sleeve is always exerted before the compression tool is advanced by a residual compression distance sR, independently of the dimensional tolerances of the pipe, the hose and the compression sleeve. The residual compression distance sR serves for also ensuring a defined deformation of the pipe so that a defined clamping between the compression sleeve, the hose and the pipe is achieved after removing the compression tool. Consequently, the pressing force between the compression sleeve, the hose and the pipe is almost independent of the dimensional tolerances of the pipe, the hose and the compression sleeve. This results in decisive improvement in the quality, lower rejection ratios and consequently more favorable manufacturing costs.
According to the invention, the objective mentioned above is also attained with a method for clamping a pipe and a hose or a second pipe with the aid of a compression sleeve, in which
a compression tool that acts upon the compression sleeve in the radial direction is advanced,
the radial force F between the compression tool and the compression sleeve is determined,
the distance s of the compression tool in the radial direction is determined,
the first derivative dF/ds of the radial force F is calculated with respect to the distance s, and
the compression tool is advanced by a residual compression distance sR after a predetermined value b of the first derivative dF/ds of the radial force with respect to the distance s is reached.
This method provides the advantage that the condition of the compressed connection can be determined even better due to the step-like progression of the first derivative of the radial force F with respect to the advance distance s before advancing the compression tool by the residual compression distance sR.
According to the invention, the objective mentioned above is also attained with a method for clamping a pipe with a hose or a second pipe with the aid of a compression sleeve, in which
a compression tool that acts upon the compression sleeve in the radial direction is advanced,
the radial force F between the compression tool and the compression sleeve is determined,
the distance s of the compression tool in the radial direction is determined,
the second derivative d2F/ds2 of the radial force F is calculated with respect to the distance s and
the compression tool is advanced by a residual compression distance sR once the number of peaks of the second derivative d2F/ds2 of the radial force F with respect to the distance (s) is equal to a predetermined number c.
The second derivative d2F/ds2 essentially contains several peaks and is otherwise approximately equal to zero. Consequently, all that is required is to determine the number of peaks in order to ascertain the degree to which the compression sleeve, the hose and the pipe are already compressed. For example, as soon as it is determined that, for example, the pipe begins to deform, the compression tool is advanced by the residual compression distance sR. This means that this method also ensures that a defined compression between the pipe, the hose and the compression sleeve is achieved after the compression tool is removed.
According to the invention, the objective mentioned above is also attained with a method for clamping a pipe with a hose or a second pipe with the aid of a compression sleeve, in which
a compression tool that acts upon the compression sleeve in the radial direction is advanced,
the radial force F between the compression tool and the compression sleeve is determined,
the distance s of the compression tool in the radial direction is determined,
the first derivative dF/ds of the radial force F is calculated with respect to the distance s,
the second derivative d2F/ds2 of the radial force F is calculated with respect to the distance s, and
the compression tool is advanced by a residual compression distance sR after a predetermined value a of the radial force F is reached, after a predetermined value b of the first derivative dF/ds of the radial force with respect to the distance s is reached, and/or after the number of peaks of the second derivative d2F/ds2 of the radial force F with respect to the distance s is equal to a predetermined number c.
This method provides the advantage that the progression of the compressed connection between the compression sleeve, the hose and the pipe is measured in three different ways. Consequently, redundant information is available. This redundancy can be used for eliminating possible outliers or the like during the determination of the values a, b or c.
According to another alternative embodiment of this method, the compression tool is only advanced by the residual compression distance when two of the three values a, b or c are reached, so that the condition of the compressed connection is determined with superior reliability.
In one variation of the method according to the invention, it is proposed that an error message is generated if the other value(s) is/are not reached during the advance. This error message indicates that the compressed connection between the compression sleeve, the hose and the pipe may not have been carried out in accordance with the pertinent specifications. Consequently, this method provides the option of carrying out a first quality control during the compression process and to reject the connections between the hose and the pipe which have not passed this first quality test. Subsequently, it would be possible, for example, to subject these rejected connections to a particularly detailed quality control in order to determine whether the connection is actually defective or adequate.
The invention also proposes that the residual compression distance sR is smaller than 0.6 mm, in particular, 0.45 mm. Due to this measure, it is ensured that an optimal connection is achieved, for example, when connecting pipes and hoses in braking systems in motor vehicles.
According to one variation of the invention, c=4 so that the centering of the compression sleeve, the plastic deformation of the compression sleeve and the compression of the hose or its outer cover is reliably completed before advancing by the residual compression distance sR.
The invention also proposes that the first peak is a positive-signed value, the second peak is a negative-signed value, and the following peaks are positive-signed values so that the negative-value peak makes it possible to reliably ascertain that the centering of the compression sleeve is completed, i.e., the determination of the condition of the compressed connection is additionally improved.